Over the last several years we have been exploring the role of the mesolimbic dopamine system in ethanol reinforcement. Our main hypothesis has been to determine, using site specific microinjection of agonists and antagonists within this system, the effects upon ethanol self- administration in an operant paradigm. Based on these findings, we know the complex interactions between these pathways and the potential specific entry point(s) for ethanol's access to these systems remains to be determined. The work proposed over the next five years will address these issues. There are 4 specific aims. Using a new behavioral technique which we have recently developed, Aim 1 we will assess the issues of specificity of site specific microinjections for ethanol reinforcement using a multiple schedule approach. Aim 2 will examine, using the same procedures, the role of the NMDA and 5HT3 receptors within this pathway to determine if they are involved with ethanol's access to this system. In Aim 3, we will use dual site microinjections to produce multiple changes within the system, in an attempt to better understand the dynamics of this system. In Aim 4, we will use another new behavioral technique, the chain schedule, to examine the role of this system in appetitive versus consummatory components of the ethanol self- administration bout. Taken together, these studies will provide more complete information as to the function of the mesolimbic mesocortical system in the control of ethanol drinking.